U.S. patent number 7,678,712 [Application Number 11/086,010] was granted by the patent office on 2010-03-16 for vapor phase treatment of dielectric materials.
This patent grant is currently assigned to Honeywell International, Inc.. Invention is credited to Anil S. Bhanap, Kikue S. Burnham, Brian J. Daniels, Denis H. Endisch, Ilan Golecki, Robert R. Roth.
United States Patent |
7,678,712 |
Bhanap , et al. |
March 16, 2010 |
Vapor phase treatment of dielectric materials
Abstract
The invention concerns a method for applying a surface
modification agent composition for organosilicate glass dielectric
films. More particularly, the invention pertains to a method for
treating a silicate or organosilicate dielectric film on a
substrate, which film either comprises silanol moieties or has had
at least some previously present carbon containing moieties removed
therefrom. The treatment adds carbon containing moieties to the
film and/or seals surface pores of the film, when the film is
porous.
Inventors: |
Bhanap; Anil S. (Milpitas,
CA), Roth; Robert R. (Sunnyvale, CA), Burnham; Kikue
S. (San Ramon, CA), Daniels; Brian J. (La Honda, CA),
Endisch; Denis H. (Cupertino, CA), Golecki; Ilan
(Parsippany, NJ) |
Assignee: |
Honeywell International, Inc.
(Morristown, NJ)
|
Family
ID: |
36263876 |
Appl.
No.: |
11/086,010 |
Filed: |
March 22, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060216952 A1 |
Sep 28, 2006 |
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Current U.S.
Class: |
438/787; 438/790;
438/781; 438/4; 257/E21.243 |
Current CPC
Class: |
H01L
21/02203 (20130101); C23C 16/56 (20130101); H01L
21/3105 (20130101); H01L 21/76814 (20130101); H01L
21/02126 (20130101); H01L 21/02337 (20130101); H01L
21/02282 (20130101); H01L 21/02216 (20130101); H01L
21/02219 (20130101); H01L 21/02222 (20130101); H01L
21/02359 (20130101) |
Current International
Class: |
H01L
21/31 (20060101) |
Field of
Search: |
;438/787,790,781,4 |
References Cited
[Referenced By]
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Primary Examiner: Ghyka; Alexander G
Attorney, Agent or Firm: Roberts; Richard S. Roberts &
Roberts, L.L.P.
Claims
What is claimed is:
1. A method for treating a silicate or organosilicate dielectric
film on a substrate, which silicate or organosilicate dielectric
film either comprises silanol moieties or which silicate or
organosilicate dielectric film has had at least some previously
present carbon containing moieties removed therefrom, the method
comprising: (a) optionally dehydrating at least a portion of a
silicate or organosilicate dielectric film on a substrate; then (b)
optionally applying an activating agent for a surface modification
agent composition to the silicate or organosilicate dielectric
film; then (c) contacting the silicate or organosilicate dielectric
film with a surface modification agent composition in a vapor or
gaseous state, wherein the surface modification agent composition
comprises a component capable of alkylating or arylating silanol
moieties or bonds created by removal of carbon containing moieties
from the silicate or organosilicate dielectric film via silylation;
wherein the surface modification agent composition comprises at
least one compound having a formula selected from the group
consisting of [--SiR.sub.2NR'--].sub.n where n>2 and may be
cyclic; R.sub.3SiNR'SiR.sub.3, (R.sub.3Si).sub.3N;
R.sub.3SiNR'.sub.2; R.sub.2Si(NR'.sub.2).sub.2;
RSi(NR'.sub.2).sub.3; R.sub.xSi[OC(R').dbd.R''].sub.4-x,
R.sub.xSi(NCOR.sub.2).sub.4-x, R.sub.xSi(NCO).sub.4-x,
R.sub.xSi(OH.sub.2).sub.4-x, and combinations thereof, wherein x is
an integer ranging from 1 to 3, each R is independently selected
from hydrogen and a hydrophobic organic moiety; R' is hydrogen, or
an organic moiety, and R'' is an alkyl or carbonyl group; and
wherein the surface modification agent composition further
comprises an activating agent selected from the group consisting of
ammonium compounds, phosphonium compounds, sulfonium compounds,
iodonium compounds, alkyl amines, aryl amines, alcohol amines,
primary amines, secondary amines, tertiary amines, ammonia,
quaternary ammonium salts, tetramethylammonium acetate,
tetrabutylammonium acetate, a combinations of tetramethylammonium
acetate and tetrabutylammonium acetate, sodium hydroxide, potassium
hydroxide lithium hydroxide and ammonium hydroxide; said contacting
being conducted under conditions sufficient to (i) or (ii) or
(iii): (i) add carbon containing moieties to the silicate or
organosilicate dielectric film, or (ii) seal surface pores of the
silicate or organosilicate dielectric film, when the film is
porous; or (iii) where the film is porous, first add carbon
containing moieties to the silicate or organosilicate dielectric
film, and then subsequently seal surface pores of the silicate or
organosilicate dielectric film.
2. A method of preventing voids in a damaged silicate or
organosilicate dielectric film on a substrate, which silicate or
organosilicate dielectric film either comprises silanol moieties or
which silicate or organosilicate dielectric film has had at least
some previously present carbon containing moieties removed
therefrom, the method comprising: (a) optionally dehydrating at
least a portion of a silicate or organosilicate dielectric film on
a substrate; then (b) applying an activating agent for a surface
modification agent composition to the silicate or organosilicate
dielectric film by chemical vapor deposition, which activating
agent is selected from the group consisting of an amine, an onium
compound, an alkali metal hydroxide, an acid, and combinations
thereof; then (c) contacting the silicate or organosilicate
dielectric film with a surface modification agent composition by
chemical vapor deposition of the surface modification agent
composition to the silicate or organosilicate dielectric film,
wherein the surface modification agent composition comprises a
component capable of alkylating or arylating silanol moieties or
bonds created by removal of carbon containing moieties from the
silicate or organosilicate dielectric film via silylation; said
contacting being conducted under conditions sufficient to either
seal surface pores of the silicate or organosilicate dielectric
film, when the film is porous; or where the film is porous, first
add carbon containing moieties to the silicate or organosilicate
dielectric film, and then subsequently seal surface pores of the
silicate or organosilicate dielectric film.
3. The method of claim 1 wherein step (a) is conducted.
4. The method of claim 1 wherein step (b) is conducted.
5. The method of claim 1 wherein step (b) is conducted by chemical
vapor deposition.
6. The method of claim 1 wherein both step (a) and step (b) are
conducted.
7. The method of claim 1 wherein step (c) is conducted by chemical
vapor deposition.
8. The method of claim 1 wherein step (c) is conducted under
conditions sufficient to add carbon containing moieties to the
silicate or organosilicate dielectric film.
9. The method of claim 1 wherein step (c) is conducted under
conditions sufficient to seal surface pores of the silicate or
organosilicate dielectric film when such film is porous.
10. The method of claim 1 wherein step (c) is conducted under
conditions sufficient to first add carbon containing moieties to
the silicate or organosilicate dielectric film, and then seal
surface pores of the silicate or organosilicate dielectric film
when such film is porous.
11. The method of claim 1 wherein the film is an organosilicate
dielectric film which has been has been previously subjected to at
least one treatment which removes at least a portion of previously
existing carbon containing moieties from the organosilicate
dielectric film.
12. The method of claim 1 wherein the silicate or organosilicate
dielectric film has been previously subjected to at least one
treatment selected from the group consisting of chemical exposure,
plasma exposure, thermal treatment, vacuum treatment, ionizing
radiation exposure, electron beam exposure, UV exposure, etching,
ashing, wet cleaning, plasma enhanced chemical vapor deposition,
supercritical fluid exposure and combinations thereof, which at
least one treatment removes at least a portion of previously
existing carbon containing moieties from the silicate or
organosilicate dielectric film.
13. The method of claim 1 wherein the silicate or organosilicate
dielectric film has been previously treated to remove from about 5
to about 95% of previously existing carbon containing moieties; and
step (c) is conducted to add carbon containing moieties to the
silicate or organosilicate dielectric film.
14. The method of claim 1 wherein the silicate or organosilicate
dielectric film comprises interconnected pores and wherein step
(c)(i) or step (c)(iii) is conducted under conditions sufficient to
add carbon containing moieties to the silicate or organosilicate
dielectric film through a depth thereof such that at least 10% of
the silanol moieties or bonds created by removal of carbon
containing moieties from the silicate or organosilicate dielectric
film are silylated.
15. The method of claim 1 wherein the silicate or organosilicate
dielectric film has pores and step (c) is conducted under
conditions sufficient to seal pores at a surface of the
organosilicate dielectric film to a depth of about 50 .ANG. or
less.
16. The method of claim 1 wherein the silicate or organosilicate
dielectric film has pores and step (c) is conducted under
conditions sufficient to seal pores at a surface of the silicate or
organosilicate dielectric film, to an extent that a subsequent
exposure to (i) precursors for chemical vapor deposition of
nitride, carbide, metals, or (ii) non-etching wet cleaning
materials does not allow a penetration thereof to a depth greater
than 5 times the maximum pore size.
17. The method of claim 1 further comprising the subsequent step
(d), after step (c) of subjecting the silicate or organosilicate
dielectric film to a treatment sufficient to effect (i) an
increased addition of carbon containing moieties to the silicate or
organosilicate dielectric film or (ii) an increased sealing of
surface pores of the silicate or organosilicate dielectric film; or
(iii) first an increased addition of carbon containing moieties to
the silicate or organosilicate dielectric film and then an
increased sealing of surface pores of the silicate or
organosilicate dielectric film or (iv) removing at least some
residual activating agent, surface modification agent, by-products;
and combinations thereof.
18. The method of claim 17 wherein step (d) is conducted by
heating, ultraviolet radiation, plasma energy, electron beam, ion
beam or combinations thereof.
19. The method of claim 1 wherein step (c) is conducted at a
temperature of from about 0.degree. C. to about 450.degree. C. for
from about 1 second to about 2 hours.
20. The method of claim 2 wherein the surface modification agent
composition further comprises at least one compound having a
formula selected from the group consisting of
acetoxytrimethylsilane, acetoxysilane, diacetoxysilane,
triacetoxysilane, diacetoxydimethylsilarie,
dimethyldiacetoxysilane, methyltriacetoxysilane,
phenyltriacetoxysilane, diphenyldiacetoxysilane,
methyltriethoxysilane, dimethyldiethoxysilane,
trimethylethoxysilane, methyltrimethoxysilane,
dimethyldimethoxysilane, trimethylmethoxysilane,
methyltrichlorosilane, dimethyldichlorosilane,
trimethyichiorosilane, methylsilane, dimethylsilane,
trimethylsilane, hexamethyldisilazane,
2-trimethylsiloxypent-2-ene-4-one, n-(trimethylsilyl)acetamide,
2-(trimethylsilyl) acetic acid, n-(trimethylsilyl)imidazole,
trimethylsilyipropiolate, trimethylsilyl(trimethylsiloxy)-acetate,
nonamethyltrisilazane, hexamethyldisiloxane, trimethylsilanol,
triethylsilanol, triphenylsilanol, t-butyldimethylsilanol,
diphenylsilanediol, trimethoxysilane, triethoxysilane,
trichlorosilane, hexamethylcyclotrisilazane,
bisdimethylaminodimethylsilane, bisdiethylaminodimethylsilane,
tris(dimethylamino)methylsilane, tris(dimethylamino)phenylsilane,
tris(dimethylamino)silane, dimethylsilyldiformamide,
dimethylsilyldiacetamide, dimethylsilyldiisocyante,
trimethylsilylisocyanate, methylsilyltriisocyanate and combinations
thereof.
21. The method of claim 1 wherein the surface modification agent
composition further comprises a corrosion inhibitor.
22. The method of claim 2 wherein the surface modification agent
composition contains said activating agent, wherein the surface
modification agent composition comprises a combination of the
activating agent and a component capable of alkylating or arylating
silanol moieties or bonds created by removal of carbon containing
moieties from the silicate or organosilicate dielectric film via
silylation.
23. The method of claim 2 wherein said contacting the silicate or
organosilicate dielectric film with a surface modification agent
composition imparts hydrophobic properties to the silicate or
organosilicate dielectric film.
24. The method of claim 2 wherein said contacting the silicate or
organosilicate dielectric film with a surface modification agent
composition is conducted under conditions sufficient either seal
surface pores of the silicate or organosilicate dielectric film,
when the film is porous; or where the film is porous, first add
carbon containing moieties to the silicate or organosilicate
dielectric film, and then subsequently seal surface pores of the
silicate or organosilicate dielectric film through at least a
portion of a depth thereof such that at least 10% of the silanol
moieties or bonds created by removal of carbon containing moieties
from the silicate or organosilicate dielectric film are silylated,
and then subsequently seal surface pores of the silicate or
organosilicate dielectric film to a depth of about 50 .ANG. or
less.
25. The method of claim 2 wherein step (a) is conducted.
26. The method of claim 2 wherein step (c) is conducted under
conditions sufficient to add carbon containing moieties to the
silicate or organosilicate dielectric film.
27. The method of claim 2 wherein step (c) is conducted under
conditions sufficient to seal surface pores of the silicate or
organoslilicate dielectric film when such film is porous.
28. The method of claim 2 wherein step (c) is conducted under
conditions sufficient to first add carbon containing moieties to
the silicate or organosilicate dielectric film, and then seal
surface pores of the silicate or organosilicate dielectric film
when such film is porous.
29. The method of claim 2 wherein the film is an organosilicate
dielectric film which has been has been previously subjected to at
least one treatment which removes at least a portion of previously
existing carbon containing moieties from the organosilicate
dielectric film.
30. The method of claim 2 wherein the silicate or organosilicate
dielectric film has been previously subjected to at least one
treatment selected from the group consisting of chemical exposure,
plasma exposure, thermal treatment, vacuum treatment, ionizing
radiation exposure, electron beam exposure, UV exposure, etching,
ashing, wet cleaning, plasma enhanced chemical vapor deposition,
supercritical fluid exposure and combinations thereof, which at
least one treatment removes at least a portion of previously
existing carbon containing moieties from the silicate or
organosilicate dielectric film.
31. The method of claim 2 wherein the silicate or organosilicate
dielectric film has been previously treated to remove from about 5
to about 95% of previously existing carbon containing moieties; and
step (c) is conducted to add carbon containing moieties to the
silicate or organosilicate dielectric film.
32. The method of claim 2 wherein the silicate or organosilicate
dielectric film has pores and step (c) is conducted under
conditions sufficient to seal pores at a surface of the
organosilicate dielectric film to a depth of about 50 .ANG. or
less.
33. The method of claim 2 wherein the silicate or organosilicate
dielectric film has pores and step (c) is conducted under
conditions sufficient to seal pores at a surface of the silicate or
organosilicate dielectric film, to an extent that a subsequent
exposure to (i) precursors for chemical vapor deposition of
nitride, carbide, metals, or (ii) non-etching wet cleaning
materials does not allow a penetration thereof to a depth greater
than 5 times the maximum pore size.
34. The method of claim 2 further comprising the subsequent step
(d), after step (c) of subjecting the silicate or organosilicate
dielectric film to a treatment sufficient to effect (i) an
increased addition of carbon containing moieties to the silicate or
organosilicate dielectric film or (ii) an increased sealing of
surface pores of the silicate or organosilicate dielectric film; or
(iii) first an increased addition of carbon containing moieties to
the silicate or organosilicate dielectric film and then an
increased sealing of surface pores of the silicate or
organosilicate dielectric film or (iv) removing at least some
residual activating agent, surface modification agent, by-products;
and combinations thereof.
35. The method of claim 2 wherein the surface modification agent
composition further comprises a corrosion inhibitor.
36. The method of claim 2wherein step (c) is conducted at a
temperature of from about 0.degree. C. to about 450.degree. C. for
from about 1 second to about 2 hours.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a method for applying a surface modification
agent composition to organosilicate glass dielectric films. More
particularly, the invention pertains to a method for treating a
silicate or organosilicate dielectric film on a substrate, which
film either comprises silanol moieties or has had at least some
previously present carbon containing moieties removed therefrom.
The treatment adds carbon containing moieties to the film and/or
seals surface pores of the film, when the film is porous. These
surface modified films are used as insulating materials in the
manufacture of semiconductor devices such as integrated circuits
("ICs"), in order to ensure low dielectric constant and stable
dielectric properties in these films.
2. Description of the Related Art
As semiconductor devices scale to lower technology nodes, the
requirement for lower and lower dielectric constant (k) has been
identified to mitigate RC delay. Similarly, as feature sizes in
integrated circuits are reduced, problems with power consumption
and signal cross-talk have become increasingly difficult to
resolve. To achieve lower dielectric constant (2.6-3.0) in dense
inorganic materials, carbon has been added to reduce the
polarizability thus reducing the dielectric constant. To achieve
ultra low dielectric constant (<2.4) materials, porosity is
added to the carbon-rich dense matrix. While the introduction of
carbon and porosity have reduced the dielectric constant, new
challenges during back end of the line processing have also been
identified. Specifically during etching and ashing, reactive gases
have been found to damage the carbon at the surface of dense
materials. Porous films having low dielectric constants have even
more deleterious effects from reactive etch and ash gases due to
diffusion through the film, which causes a greater extent of damage
at the internal pore walls. Once the carbon has been damaged, the
films rehydroxylate and hydrogen bond with water. Because water has
a dielectric constant of 70, small amounts that are absorbed for
dense materials and adsorbed for porous materials cause the
dielectric constant to go up significantly. Also, porous materials
tend to void after copper annealing due to the high tensile stress
fields which will destroy device yields. None of these are
acceptable and lead to unviable materials.
It is believed that the integration of low dielectric constant
materials for interlevel dielectric (ILD) and intermetal dielectric
(IMD) applications will help to solve these problems. While there
have been previous efforts to apply low dielectric constant
materials to integrated circuits, there remains a longstanding need
in the art for further improvements in processing methods and in
the optimization of both the dielectric and mechanical properties
of such materials. Device scaling in future integrated circuits
clearly requires the use of low dielectric constant materials as a
part of the interconnect structure. Most candidates for low
dielectric constant materials for use in sub-100 nm generation ICs
are carbon containing SiO.sub.2 films formed by either CVD or
spin-on methods. During subsequent processing steps, such as plasma
etching and photoresist removal using plasma or wet strip methods,
significant damage occurs to these low-k materials, that causes
fluorine addition and carbon depletion from the low-k material
adjacent to the etched surface. In addition to a higher effective
dielectric constant, the resultant structures are susceptible to
void formation, outgassing and blister formation. The voids in turn
may cause an increase in leakage current at elevated voltages and
reduction in breakdown voltage. The present invention describes a
way to reduce the damage and resulting issues by treating the
wafers with silylating agents by a vapor deposition process such as
chemical vapor deposition.
One way to approach this challenge is to repair the damaged area on
dense surfaces, or in the case of porous materials on the internal
pore walls with a re-methylating compound called a surface
modification agent. Surface modification agents react with
re-hydroxylated surfaces and re-alkylate or re-arylate them which
in-turn restores the dielectric constant. In the case of porous
internal pore wall surfaces, the re-methylation prevents void
formation. Many times, the use of a surface modification agent
allows for conventional etch and ash processes to be utilized with
low and ultra low dielectric constant materials. The treatment
could result in replenishment of carbon to the low-k film, usually
restoring hydrophobicity and resistance to further damage during a
wet cleaning operation. Additionally, it would be desirable if the
repaired low-k material was found to be resistant to void
formation, which generally occurs in untreated porous low
dielectric inter-level dielectric regions during copper annealing
processes. Silylating agents ("surface modification agents") can
methylate the surface of SiO.sub.2 based materials. Contemplated
exposure includes vapor exposure with or without plasma. Normally,
SiCOH based porous low-k materials are susceptible to void
formation in ILD during Cu damascene processing. After a surface
modification agent treatment, the resulting structure is
significantly more resistant to void formation. Without being bound
to any specific theory or mechanism, it is believed that plasma
damage causes carbon depletion in the dielectric, by replacing
Si--CH.sub.3 bonds with Si--OH bonds. In damaged porous
dielectrics, the pore surface is now covered with Si--OH bonds. In
the presence of tensile stress (such as after Cu annealing),
adjacent Si--OH groups can condense, thus causing local
densification. The evolving reaction products and the stretching of
the molecules due to the new links formed, causes voids to occur
near the center of the ILD space. Surface modification agents
prevent void formation by replacing most Si--OH bonds by
Si--O--Si--Rx bonds, which avoid condensation reactions. Therefore
void formation does not occur.
In addition, it is also known that existence of the
SiO--SiR.sub.2--OSi linkage (where the SiR.sub.2 is one example of
a surface modification functionality within the matrix), that the
modulus of the porous material should improve. Modulus retention
and improvement is required for most porous materials to withstand
imposed stresses. The surface modifying linkage, e.g., a
dimethylsilyl linkage, clearly improves the modulus. If applied to
weakened areas of the silicate, an improvement of the material to
external stress is expected.
The surface modification treatment performed after dielectric
trench and via formation and etching and ashing steps repairs
carbon depletion and damage to the low-k materials. By this means,
voids are deterred and the later can withstand internal stresses
caused by annealing treatments to the metal filling the trenches
and vias.
The surface modifying treatment is conducted by exposing the wafer
surface to the silylating agent in liquid or gas form for a period
sufficient to complete the reaction with the damaged low dielectric
constant region. Optionally, further treatments can be done, e.g. a
high temperature bake to remove remaining solvent, excess surface
modification agent, and by-products. Also, optionally, a wet
cleaning operation can be performed immediately after the surface
modification agent application, or after the baking step, using a
commercially available chemical compatible with the low-k
dielectric. Additionally a dehydration bake may be performed before
the surface modification agent treatment, to increase effectiveness
of the surface modification agent treatment.
The effectiveness of the surface modification agent treatment can
be verified using unpatterned low-k dielectric films subjected to
etching and ashing processing followed by the surface modification
agent treatment. A successful surface modification agent treatment
results in increased carbon concentration that can be measured by
FTIR, EDX, or XPS techniques. Additionally, a water contact angle
increase is seen, which demonstrates the hydrophobic nature of the
post-treatment surface. The surface modification agent treated film
also shows a lower dielectric constant compared to an etched/ashed
film that is not treated with surface modification agent. In
patterned wafers, the effectiveness of the surface modification
agent treatment is demonstrated by reduction or elimination of
voids in the low-k dielectric in narrow spaces between copper
trenches after a copper anneal treatment following electroplating
of copper, and also by lower profile change in trenches or vias
after exposure to reactive solvents. It has been found that the
effectiveness of silane based surface modification agents is
enhances by an activating agent such as an amine, an onium compound
or an alkali metal hydroxide.
SUMMARY OF THE INVENTION
The invention provides a method for treating a silicate or
organosilicate dielectric film on a substrate, which silicate or
organosilicate dielectric film either comprises silanol moieties or
which silicate or organosilicate dielectric film has had at least
some previously present carbon containing moieties removed
therefrom, the method comprising:
(a) optionally dehydrating at least a portion of a silicate or
organosilicate dielectric film on a substrate; then
(b) optionally applying an activating agent for a surface
modification agent composition to the silicate or organosilicate
dielectric film; then
(c) contacting the silicate or organosilicate dielectric film with
a surface modification agent composition in a vapor or gaseous
state, wherein the surface modification agent composition comprises
a component capable of alkylating or arylating silanol moieties or
bonds created by removal of carbon containing moieties from the
silicate or organosilicate dielectric film via silylation; said
contacting being conducted under conditions sufficient to (i) or
(ii) or (iii): (i) add carbon containing moieties to the silicate
or organosilicate dielectric film, or (ii) seal surface pores of
the silicate or organosilicate dielectric film, when the film is
porous; or (iii) first add carbon containing moieties to the
silicate or organosilicate dielectric film, and then seal surface
pores of the silicate or organosilicate dielectric film, when the
film is porous.
The invention also provides a method of preventing voids in a
damaged silicate or organosilicate dielectric film on a substrate,
which silicate or organosilicate dielectric film either comprises
silanol moieties or which silicate or organosilicate dielectric
film has had at least some previously present carbon containing
moieties removed therefrom, the method comprising:
(a) optionally dehydrating at least a portion of a silicate or
organosilicate dielectric film on a substrate; then
(b) optionally applying an activating agent for a surface
modification agent composition to the silicate or organosilicate
dielectric film by chemical vapor deposition; then
(c) contacting the silicate or organosilicate dielectric film with
a surface modification agent composition by chemical vapor
deposition of the surface modification agent composition to the
silicate or organosilicate dielectric film, wherein the surface
modification agent composition comprises a component capable of
alkylating or arylating silanol moieties or bonds created by
removal of carbon containing moieties from the silicate or
organosilicate dielectric film via silylation; said contacting
being conducted under conditions sufficient to add carbon
containing moieties to the silicate or organosilicate dielectric
film through at least a portion of a depth thereof.
The invention further provides a method of imparting hydrophobic
properties to a silicate or organosilicate dielectric film on a
substrate, which silicate or organosilicate dielectric film either
comprises silanol moieties or which silicate or organosilicate
dielectric film has had at least some previously present carbon
containing moieties removed therefrom, the method comprising:
(a) optionally dehydrating at least a portion of a silicate or
organosilicate dielectric film on a substrate; then
(b) optionally applying an activating agent for a surface
modification agent composition to the silicate or organosilicate
dielectric film by chemical vapor deposition; then
(c) contacting the silicate or organosilicate dielectric film with
a surface modification agent composition by chemical vapor
deposition of the surface modification agent composition to the
silicate or organosilicate dielectric film, wherein the surface
modification agent composition comprises a component capable of
alkylating or arylating silanol moieties or bonds created by
removal of carbon containing moieties from the silicate or
organosilicate dielectric film via silylation; said contacting
being conducted under conditions sufficient to (i) or (ii) or
(iii): (i) add carbon containing moieties to the silicate or
organosilicate dielectric film through at least a portion of a
depth thereof, or (ii) seal surface pores of the silicate or
organosilicate dielectric film; or (iii) first add carbon
containing moieties to the silicate or organosilicate dielectric
film through at least a portion of a depth thereof, and then seal
surface pores of the silicate or organosilicate dielectric
film.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of an equipment configuration
for performing the inventive method.
FIG. 2 is a schematic representation of another equipment
configuration for performing the inventive method.
FIG. 3 is a schematic representation of yet another equipment
configuration for performing the inventive method.
DETAILED DESCRIPTION OF THE INVENTION
In the context of the present invention, dielectric materials
having low dielectric constants, typically below 3 are especially
desirable because they typically allow faster signal propagation,
reduce capacitive effects and cross talk between conductor lines,
and lower voltages to drive integrated circuits. This invention
relates to both porous and non-porous dielectric materials. One
material with a low dielectric constant is silica which can be
applied as a foamed dielectric material. For the lowest possible
dielectric values, air is introduced into silica dielectric
materials. Air has a dielectric constant of 1, and when air is
introduced into a silica dielectric material in the form of
nanoporous or nanometer-scale pore structures, relatively low
dielectric constants are achieved. It should be understood that
unless the "SiO.sub.2" functional group is specifically mentioned
when the term "silica" is employed, the term "silica" as used
herein, for example, with reference to porous and non-porous
dielectric films, is intended to refer to silicate and
organosilicate dielectric films prepared from an organic or
inorganic glass base material, e.g., any suitable starting material
containing one or more silicon-based dielectric precursors. It
should also be understood that the use of singular terms herein is
not intended to be so limited, but, where appropriate, also
encompasses the plural, e.g., exemplary processes of the invention
may be described as applying to and producing a "film" but it is
intended that multiple films can be produced by the described,
exemplified and claimed processes, as desired. The term, "film" as
used herein with regard to the dielectric materials is intended to
encompass any other suitable form or shape in which such silica
dielectric materials are optionally employed. Nanoporous silica is
attractive because it employs similar precursors, including
organic-substituted silanes, e.g., tetramethoxysilane ("TMOS")
and/or tetraethoxysilane ("TEOS"), as are used for the currently
employed spin-on-glasses ("SOG") and chemical vapor disposition
("CVD") silica SiO.sub.2. As used herein, the terms "void" and
"pore" mean a free volume in which a mass is replaced with a gas or
where a vacuum is generated. The composition of the gas is
generally not critical, and appropriate gases include relatively
pure gases and mixtures thereof, including air. The nanoporous
polymer may comprise a plurality of pores. Pores are typically
spherical, but may alternatively or additionally have any suitable
shape, including tubular, lamellar, discoidal, or other shapes. The
pores may be uniformly or randomly dispersed within the porous
polymer. It is also contemplated that the pores may have any
appropriate diameter. It is further contemplated that at least some
pores may connect with adjacent pores to create a structure with a
significant amount of connected or "open" porosity.
Nanoporous silica films have previously been fabricated by a number
of methods. Suitable silicon-based precursor compositions and
methods for forming nanoporous silica dielectric films, are
described, for example, by the following co-owned U.S. Pat. Nos.
6,048,804, 6,022,812; 6,410,149; 6,372,666; 6,509,259; 6,218,497;
6,143,855, 6,037,275; 6,042,994; 6,048,804; 6,090,448; 6,126,733;
6,140,254; 6,204,202; 6,208,041; 6,318,124 and 6,319,855 all
incorporated herein by reference herein.
Other dielectric and low dielectric materials comprise
inorganic-based compounds, such as the silicon-based disclosed in
commonly assigned pending U.S. patent application Ser. No.
10/078,919 filed Feb. 19, 2002; (for example NANOGLASS.RTM. and
HOSP.RTM. products commercially available from Honeywell
International Inc.). The dielectric and low dielectric materials
may be applied by spin coating the material on to the surface, dip
coating, spray coating, chemical vapor deposition (CVD), rolling
the material onto the surface, dripping the material on to the
surface, and/or spreading the material onto the surface.
Dielectrics useful for this invention include CVD deposited
materials, such as carbon doped oxides for example, Black Diamond,
commercially available from Applied Materials, Inc., Coral,
commercially available from Novellus, Aurora, which is commercially
available from ASM, and Orion, which is commercially available from
Trikon.
As used herein, the phrases "spin-on material", "spin-on organic
material", "spin-on composition" and "spin-on inorganic
composition" may be used interchangeable and refer to those
solutions and compositions that can be spun-on to a substrate or
surface using the spin coating application process. Examples of
silicon-based compounds comprise siloxane compounds, such as
methylsiloxane, methylsilsesquioxane, phenylsiloxane,
phenylsilsesquioxane, methylphenylsiloxane,
methylphenylsilsesquioxane, silazane polymers, silicate polymers
and mixtures thereof. A contemplated silazane polymer is
perhydrosilazane, which has a "transparent" polymer backbone where
chromophores can be attached. Spin-on-glass materials also includes
siloxane polymers and block polymers, hydrogensiloxane polymers of
the general formula (H.sub.0-1.0SiO.sub.1.5-2.0).sub.x and
hydrogensilsesquioxane polymers, which have the formula
(HSiO.sub.1.5).sub.x, where x is greater than about four. Also
included are copolymers of hydrogensilsesquioxane and an
alkoxyhydridosiloxane or hydroxyhydridosiloxane. Spin-on glass
materials additionally include organohydridosiloxane polymers of
the general formula
(H.sub.0-1.0SiO.sub.1.5-2.0).sub.n(R.sub.0-1.0SiO.sub.1.5-2.0).su-
b.m, and organohydridosilsesquioxane polymers of the general
formula (HSiO.sub.1.5).sub.n(RSiO.sub.1.5).sub.m, where m is
greater than zero and the sum of n and m is greater than about four
and R is alkyl or aryl. Some useful organohydridosiloxane polymers
have the sum of n and m from about four to about 5000 where R is a
C.sub.1-C.sub.20 alkyl group or a C.sub.6-C.sub.12 aryl group. The
organohydridosiloxane and organohydridosilsesquioxane polymers are
alternatively denoted spin-on-polymers. Some specific examples
include alkylhydridosiloxanes, such as methylhydridosiloxanes,
ethylhydridosiloxanes, propylhydridosiloxanes,
t-butylhydridosiloxanes, phenylhydridosiloxanes; and
alkylhydridosilsesquioxanes, such as methylhydridosilsesquioxanes,
ethylhydridosilsesquioxanes, propylhydridosilsesquioxanes,
t-butylhydridosilsequioxanes, phenylhydridosilsesquioxanes, and
combinations thereof. Several of the contemplated spin-on materials
are described in the following issued patents and pending
applications, which are herein incorporated by reference in their
entirety: U.S. Pat. Nos. 6,506,497; 6,365,765; 6,268,457;
6,177,199; 6,358,559; 6,218,020; 6,361,820; 6,218,497; 6,359,099;
6,143,855; 6,512,071, U.S. patent application Ser. No. 10/001,143
filed Nov. 10, 2001; PCT/US00/15772 filed Jun. 8, 2000, and
PCT/US00/00523 filed Jan. 7, 1999.
Solutions of organohydridosiloxane and organosiloxane resins can be
utilized for forming caged siloxane polymer films that are useful
in the fabrication of a variety of electronic devices,
micro-electronic devices, particularly semiconductor integrated
circuits and various layered materials for electronic and
semiconductor components, including hard mask layers, dielectric
layers, etch stop layers and buried etch stop layers. These
organohydridosiloxane resin layers are compatible with other
materials that might be used for layered materials and devices,
such as adamantane-based compounds, diamantane-based compounds,
silicon-core compounds, organic dielectrics, and nanoporous
dielectrics. Compounds that are considerably compatible with the
organohydridosiloxane resin layers contemplated herein are
disclosed in U.S. Pat. Nos. 6,214,746; 6,171,687; 6,172,128;
6,156,812, U.S. Application Ser. No. 60/350,187 filed Jan. 15,
2002; U.S. patent application Ser. No. 09/538,276; U.S. patent
application Ser. No. 09/544,504; U.S. patent application Ser. No.
09/587,851; and U.S. 60/347,195 filed Jan. 8, 2002; PCT Application
PCT/US01/32569 filed Oct. 17, 2001; PCT Application PCT/US01/50812
filed Dec. 31, 2001, which are all incorporated herein by
reference.
Suitable organohydridosiloxane resins utilized herein have the
following general formulas: [H--Si.sub.1.5].sub.n[R--SiO.sub.1.5]hd
m Formula (1)
[H.sub.0.5--Si.sub.1.5-1.8].sub.n[R.sub.0.5-1.0--SiO.sub.1.5-1.8].sub.m
Formula (2) [H.sub.0-1.0--Si.sub.1.5].sub.n[R--SiO.sub.1.5].sub.m
Formula (3)
[H--Si.sub.1.5].sub.x[R--SiO.sub.1.5].sub.y[SiO.sub.2].sub.z
Formula (4) wherein: the sum of n and m, or the sum or x, y and z
is from about 8 to about 5000, and m or y is selected such that
carbon containing constituents are present in either an amount of
less than about 40 percent (Low Organic Content=LOSP) or in an
amount greater than about 40 percent (High Organic Content=HOSP); R
is selected from substituted and unsubstituted, normal and branched
alkyls (methyl, ethyl, butyl, propyl, pentyl), alkenyl groups
(vinyl, allyl, isopropenyl), cycloalkyls, cycloalkenyl groups,
aryls (phenyl groups, benzyl groups, naphthalenyl groups,
anthracenyl groups and phenanthrenyl groups), and mixtures thereof,
and wherein the specific mole percent of carbon containing
substituents is a function of the ratio of the amounts of starting
materials. In some LOSP embodiments, particularly favorable results
are obtained with the mole percent of carbon containing
substituents being in the range of between about 15 mole percent to
about 25 mole percent. In some HOSP embodiments, favorable results
are obtained with the mole percent of carbon containing
substituents are in the range of between about 55 mole percent to
about 75 mole percent.
Nanoporous silica dielectric films with dielectric constants
ranging from about 1.5 to about 4 can also be used as one of the
layers. Nanoporous silica films are laid down as a silicon-based
precursor, aged or condensed in the presence of water and heated
sufficiently to remove substantially all of the porogen and to form
voids in the film. The silicon-based precursor composition
comprises monomers or prepolymers that have the formula:
R.sub.x--Si--L.sub.y, wherein R is independently selected from
alkyl groups, aryl groups, hydrogen and combinations thereof, L is
an electronegative moiety, such as alkoxy, carboxy, amino, amido,
halide, isocyanato and combinations thereof, x is an integer
ranging from 0 to about 2, and y is an integer ranging from about 2
to about 4. Other nanoporous compounds and methods can be found in
U.S. Pat. Nos. 6,171,687; 6,172,128; 6,214,746; 6,313,185;
6,380,347; and 6,380,270, which are incorporated herein in their
entirety.
The phrases "cage structure", "cage molecule", and "cage compound"
are intended to be used interchangeably and refer to a molecule
having at least 10 atoms arranged such that at least one bridge
covalently connects two or more atoms of a ring system. In other
words, a cage structure, cage molecule or cage compound comprises a
plurality of rings formed by covalently bound atoms, wherein the
structure, molecule or compound defines a volume, such that a point
located with the volume can not leave the volume without passing
through the ring. The bridge and/or the ring system may comprise
one or more heteroatoms, and may be aromatic, partially saturated,
or unsaturated. Further contemplated cage structures include
fullerenes, and crown ethers having at least one bridge. For
example, an adamantane or diamantane is considered a cage
structure, while a naphthalene compound or an aromatic spiro
compound are not considered a cage structure under the scope of
this definition, because a naphthalene compound or an aromatic
spiro compound do not have one, or more than one bridge.
Contemplated cage compounds need not necessarily be limited to
being comprised solely of carbon atoms, but may also include
heteroatoms such as N, S, O, P, etc. Heteroatoms may advantageously
introduce non-tetragonal bond angle configurations. With respect to
substituents and derivatizations of contemplated cage compounds, it
should be recognized that many substituents and derivatizations are
appropriate. For example, where the cage compounds are relatively
hydrophobic, hydrophilic substituents may be introduced to increase
solubility in hydrophilic solvents, or vice versa. Alternatively,
in cases where polarity is desired, polar side groups may be added
to the cage compound. It is further contemplated that appropriate
substituents may also include thermolabile groups, nucleophilic and
electrophilic groups. It should also be appreciated that functional
groups may be utilized in the cage compound (e.g., to facilitate
crosslinking reactions, derivatization reactions, etc.). Cage
molecules or compounds, as described in detail herein, can also be
groups that are attached to a polymer backbone, and therefore, can
form nanoporous materials where the cage compound forms one type of
void (intramolecular) and where the crosslinking of at least one
part of the backbone with itself or another backbone can form
another type of void (intermolecular). Additional cage molecules,
cage compounds and variations of these molecules and compounds are
described in detail in PCT/US01/32569 filed on Oct. 18, 2001, which
is herein incorporated by reference in its entirety. Contemplated
polymers may also comprise a wide range of functional or structural
moieties, including aromatic systems, and halogenated groups.
Furthermore, appropriate polymers may have many configurations,
including a homopolymer, and a heteropolymer. Moreover, alternative
polymers may have various forms, such as linear, branched,
super-branched, or three-dimensional. The molecular weight of
contemplated polymers spans a wide range, typically between 400
Dalton and 400000 Dalton or more. Additives can also be used to
enhance or impart particular properties, as is conventionally known
in the polymer art, including stabilizers, flame retardants,
pigments, plasticizers, surfactants, and the like. Compatible or
non-compatible polymers can be blended in to give a desired
property. Adhesion promoters can also be used. Such promoters are
typified by hexamethyldisilazane, which can be used to interact
with available hydroxyl functionality that may be present on a
surface, such as silicon dioxide, that was exposed to moisture or
humidity. Polymers for microelectronic applications desirably
contain low levels (generally less than 1 ppm, preferably less than
10 ppb) of ionic impurities, particularly for dielectric
interlayers.
The materials, precursors and layers described herein can be and in
many ways are designed to be solvated or dissolved in any suitable
solvent, so long as the resulting solutions can be applied to a
substrate, a surface, a wafer or layered material. Typical solvents
are also those solvents that are able to solvate the monomers,
isomeric monomer mixtures and polymers. Contemplated solvents
include any suitable pure or mixture of organic or inorganic
molecules that are volatilized at a desired temperature, such as
the critical temperature, or that can facilitate any of the
above-mentioned design goals or needs. The solvent may also
comprise any suitable single polar and non-polar compounds or
mixture thereof. As used herein, the term "polar" means that
characteristic of a molecule or compound that creates an unequal
charge, partial charge or spontaneous charge distribution at one
point of or along the molecule or compound. As used herein, the
term "non-polar" means that characteristic of a molecule or
compound that creates an equal charge, partial charge or
spontaneous charge distribution at one point of or along the
molecule or compound. In some contemplated embodiments, the solvent
or solvent mixture (comprising at least two solvents) comprises
those solvents that are considered part of the hydrocarbon family
of solvents. Hydrocarbon solvents are those solvents that comprise
carbon and hydrogen. It should be understood that a majority of
hydrocarbon solvents are non-polar; however, there are a few
hydrocarbon solvents that could be considered polar. Hydrocarbon
solvents are generally broken down into three classes: aliphatic,
cyclic and aromatic. Aliphatic hydrocarbon solvents may comprise
both straight-chain compounds and compounds that are branched and
possibly crosslinked, however, aliphatic hydrocarbon solvents are
not considered cyclic. Cyclic hydrocarbon solvents are those
solvents that comprise at least three carbon atoms oriented in a
ring structure with properties similar to aliphatic hydrocarbon
solvents. Aromatic hydrocarbon solvents are those solvents that
comprise generally three or more unsaturated bonds with a single
ring or multiple rings attached by a common bond and/or multiple
rings fused together. Contemplated hydrocarbon solvents include
toluene, xylene, p-xylene, m-xylene, mesitylene, solvent naphtha H,
solvent naphtha A, alkanes, such as pentane, hexane, isohexane,
heptane, nonane, octane, dodecane, 2-methylbutane, hexadecane,
tridecane, pentadecane, cyclopentane, 2,2,4-trimethylpentane,
petroleum ethers, halogenated hydrocarbons, such as chlorinated
hydrocarbons, nitrated hydrocarbons, benzene, 1,2-dimethylbenzene,
1,2,4-trimethylbenzene, mineral spirits, kerosene, isobutylbenzene,
methylnaphthalene, ethyltoluene, ligroine. Particularly
contemplated solvents include, but are not limited to, pentane,
hexane, heptane, cyclohexane, benzene, toluene, xylene and mixtures
or combinations thereof.
In other contemplated embodiments, the solvent or solvent mixture
may comprise those solvents that are not considered part of the
hydrocarbon solvent family of compounds, such as ketones, such as
acetone, 3-pentanone, diethyl ketone, methyl ethyl ketone and the
like, alcohols, ketones, esters, ethers and amines. In yet other
contemplated embodiments, the solvent or solvent mixture may
comprise a combination of any of the solvents mentioned herein. In
some embodiments, the solvent comprises water, ethanol, propanol,
acetone, ethylene oxide, benzene, toluene, ethers, cyclohexanone,
butyrolactone, methylethylketone, and anisole.
It is still further contemplated that alternative low dielectric
constant material may also comprise additional components. For
example, where the low dielectric constant material is exposed to
mechanical stress, softeners or other protective agents may be
added. In other cases where the dielectric material is placed on a
smooth surface, adhesion promoters may advantageously employed. In
still other cases, the addition of detergents or antifoam agents
may be desirable. In general, a precursor in the form of, e.g., a
spin-on-glass composition that includes one or more removable
solvents, is applied to a substrate, and then polymerized and
subjected to solvent removal in such a way as to form a dielectric
film comprising nanometer-scale pores.
When forming such nanoporous films, e.g., wherein the precursor is
applied to a substrate by spin-coating, the film coating is
typically catalyzed with an acid or base catalyst and water to
cause polymerization/gelation ("aging") during an initial heating
step. The film is then cured, e.g., by subjecting the film to one
or more higher temperature heating steps to, inter alia, remove any
remaining solvent and complete the polymerization process, as
needed. Other curing methods include subjecting the film to radiant
energy, e.g., ultraviolet, electron beam, microwave energy, and the
like.
U.S. Pat. Nos. 6,204,202 and 6,413,882, incorporated by reference
herein, provide silicon-based precursor compositions and methods
for forming nanoporous silica dielectric films by degrading or
vaporizing one or more polymers or oligomers present in the
precursor composition. U.S. Pat. No. 6,495,479, provides
silicon-based precursor compositions and methods for forming
nanoporous silica dielectric films by degrading or vaporizing one
or more compounds or polymers present in the precursor composition.
U.S. Pat. No. 5,895,263 describes forming a nanoporous silica
dielectric film on a substrate, e.g., a wafer, by applying a
composition comprising decomposable polymer and organic polysilica
i.e., including condensed or polymerized silicon polymer, heating
the composition to further condense the polysilica, and decomposing
the decomposable polymer to form a porous dielectric layer.
Processes for application of precursor to a substrate, aging,
curing, planarization, and rendering the film(s) hydrophobic are
described, for example, in U.S. Pat. Nos. 6,589,889 and 6,037,275,
among others. Substrates and wafers contemplated herein may
comprise any desirable substantially solid material. Particularly
desirable substrate layers would comprise films, glass, ceramic,
plastic, metal or coated metal, or composite material. In preferred
embodiments, the substrate comprises a silicon or germanium
arsenide die or wafer surface, a packaging surface such as found in
a copper, silver, nickel or gold plated leadframe, a copper surface
such as found in a circuit board or package interconnect trace, a
via-wall or stiffener interface ("copper" includes considerations
of bare copper and it's oxides), a polymer-based packaging or board
interface such as found in a polyimide-based flex package, lead or
other metal alloy solder ball surface, glass and polymers such as
polyimide. The "substrate" may even be defined as another polymer
chain when considering cohesive interfaces. In more preferred
embodiments, the substrate comprises a material common in the
packaging and circuit board industries such as silicon, copper,
glass, and another polymer.
Subsequent semiconductor manufacturing processes such as deposition
of cap film by PECVD techniques, and via and trench formation by
patterning by means of etching and ashing, atomic layer deposition,
physical vapor deposition, and a chemical vapor deposition
treatment tend to remove carbon containing moieties which are
hydrophobic groups from the organosilicate glass dielectric films
and replace them with silanol groups. Undesirable properties result
when the organosilicate glass dielectric films contain silanol
groups. Silanols, and the water that they can adsorb from the air
are highly polarizable in an electric field, and thus will raise
the dielectric constant of the film, and will lower resistance to
wet cleaning chemistries and increase volatile evolution. Also,
when the trenches and vias are filled with a metal and subjected to
an annealing treatment, metal shrinkage induces a stress on the via
and trench walls and cause undesirable voids to form inside the
dielectric material between the vias and trenches. When the film is
an organosilicate dielectric film, it has often been has been
previously subjected to at least one damaging treatment which
removes at least a portion of previously existing carbon containing
moieties from the organosilicate dielectric film. Such film damage
can result from such treatments as chemical exposure, plasma
exposure, thermal treatment, vacuum treatment, ionizing radiation
exposure, electron beam exposure, UV exposure, etching, ashing, wet
cleaning, plasma enhanced chemical vapor deposition, supercritical
fluid exposure and combinations thereof. These treatments remove at
least a portion of previously existing carbon containing moieties
from the silicate or organosilicate dielectric film. Typically
these treatments remove from about 5 to about 95% of previously
existing carbon containing moieties. The inventive process is
conducted to add back these carbon containing moieties to the
silicate or organosilicate dielectric film.
In order to remedy this problem, the organosilicate glass
dielectric films are made substantially free of silanols and water
by treatment with a surface modification agent to restore carbon
containing moieties and usually increase the hydrophobicity of the
organosilicate glass dielectric film. This makes the film resistant
to stresses, such as induced by metal shrinkage during annealing,
stress from other dielectric layers, and stress during packaging,
thus deters undesirable voids from forming inside the dielectric
material between the vias and trenches.
Etching and plasma remove hydrophobic functional groups. Damage to
organosilicate glass dielectric films during semiconductor
manufacturing processes results from the application of aggressive
plasmas and/or etching reagents to etch trenches and vias into
dielectric films. Plasmas are also used to remove photoresist films
during fabrication of semiconductor devices. The plasmas used are
typically composed of the elements oxygen, fluorine, hydrogen,
carbon, argon, helium or nitrogen (in the form of free atoms,
compounds, ions and/or radicals).
Dielectric films which are exposed to these plasmas during trench,
via, etch and/or photoresist removal are easily degraded or
damaged. Porous dielectric films have a very high surface area and
are therefore particularly vulnerable to plasmas damage. In
particular, silica based dielectric films which have organic
content (such as methyl groups bonded to Si atoms) are readily
degraded by oxygen plasmas. The organic group is oxidized into
CO.sub.2 and a silanol or Si--OH group remains on the dielectric
surface where the organic group formerly resided. Porous and
non-porous low dielectric constant silica films depend on such
organic groups (on surfaces) to remain hydrophobic. Loss of the
hydrophobicity makes the dielectric constant rise (the low
dielectric constant of such films is the key desired property of
such materials).
Wet chemical treatments are also used in IC production for the
purpose of removing residues leftover after trench or via etching.
The chemicals used are often so aggressive they will attack and
remove organic groups in silica based dielectric films, especially
porous silica films. Again, this damage will cause the films to
lose their hydrophobicity. Wet chemical etchants include, for
example, amides, such as N-methylpyrrolidinone, dimethylformamide,
dimethylacetamide; alcohols such as ethanol and 2-propanol;
alcoholamines such as ethanolamine; amines such as triethylamine;
diamines such as ethylenediamine and N,N-diethylethylenediamine;
triamines such as diethylenetriamine, diamine acids such as
ethylenediaminetetracetic acid "EDTA"; organic acids such as acetic
acid and formic acid; the ammonium salts of organic acids such as
tetramethylammonium acetate; inorganic acids such as sulfuric acid,
phosphoric acid, hydrofluoric acid; fluoride salts such as ammonium
fluoride; and bases such as ammonium hydroxide and tetramethyl
ammonium hydroxide; and hydroxyl amine; commercial formulations
developed for post etch wet cleaning such as EKC 505, 525, 450,
265, 270, and 630 (EKC Corp., Hayward Calif.), and ACT-CMI and
ACT-690 (Ashland Chemical, Hayward, Calif.). to name but a few
art-known etchants. Ashing agents include plasmas derived from
hydrogen, nitrogen, helium, argon, oxygen, and mixtures derived
therefrom, and the like.
In order to solve the above mentioned problems the inventive
treatment methods imparting desirable properties to dielectric
films present on a substrate during the process of fabricating a
semiconductor or IC device.
The first step of the inventive process is an optional but
preferred step of dehydrating at least a portion of a silicate or
organosilicate dielectric film on a substrate. Such may be done by
any means known in the art such as heating at a temperature of from
about 20.degree. C. to about 450.degree. C., preferably from about
100.degree. C. to about 400.degree. C. for from about 10 seconds to
about 4 hours, preferably from about 1 minute to 120 minutes, and
more preferably from about 10 seconds to about 30 minutes. The
dehydration bake removes substantially all of the moisture which
may have been adsorbed in the dielectric film. Removal of moisture
from the dielectric prior to surface modification agent treatment
renders the subsequent treatments more effective.
The next step of the inventive process is an optional but preferred
step of applying an activating agent for a surface modification
agent composition to the silicate or organosilicate dielectric
film. Useful activating agents non-exclusively include amines,
onium compounds and alkali metal hydroxides. Useful activating
agents include ammonium compounds, phosphonium compounds, sulfonium
compounds and iodonium compounds. Included are activating agents
which may be alkyl amines, aryl amines, alcohol amines and mixtures
thereof which suitably have a boiling point of about 100.degree. C.
or higher, usually about 125.degree. C. or higher and more usually
about 150.degree. C. or higher. Catalyst exposure may be conducted
by applying a gas or vapor of the activating agent to the film on
the substrate at a temperature of from about 20.degree. C. to about
450.degree. C., preferably from about 100.degree. C. to about
400.degree. C. for from about 10 seconds to about 30 minutes,
preferably from about 1 minute to 30 minutes.
Useful amine activating agent include primary amines, secondary
amines, tertiary amines, ammonia, and quaternary ammonium salts.
Useful amines are monoethanolamine, diethanolamine,
triethanolamine, monoisopropanolamine, tetraethylenepentamine,
2-(2-aminoethoxy)ethanol; 2-(2-aminoethylamino)ethanol and mixtures
thereof. In a desired embodiment of the invention the activating
agent comprises tetramethylammonium acetate, tetrabutylammonium
acetate or combinations thereof. Other activating agents include
sodium hydroxide, potassium hydroxide, lithium hydroxide and
ammonium hydroxide. The activating agent may be applied to the film
by any convenient method such as coating, spin-on, dipping, vapor
application, chemical vapor deposition, and the like. The
activating agent is usually applied to the film amount of from
about 0.0001 weight percent to about 10 weight percent, more
usually from about 0.001 weight percent to about 1 weight percent,
and most usually from about 0.01 weight percent to about 0.1 weight
percent, based on the weight of the subsequently applied surface
modification agent composition.
The next step in the inventive method is contacting the silicate or
organosilicate dielectric film with a surface modification agent
composition in a vapor or gaseous state. For purposes of this
invention, such contacting of the silicate or organosilicate
dielectric film with a surface modification agent composition is
defined as a contacting of the film which either has or has not
been first dehydrated and has or has not been contacted with an
activating agent for the surface modification agent.
The surface modification agent composition comprises a component
capable of alkylating or arylating silanol moieties or bonds
created by removal of carbon containing moieties from the silicate
or organosilicate dielectric film via silylation; said contacting
being conducted under conditions sufficient to (i) or (ii) or
(iii):
(i) add carbon containing moieties to the silicate or
organosilicate dielectric film, or
(ii) seal surface pores of the silicate or organosilicate
dielectric film, when the film is porous; or
(iii) first add carbon containing moieties to the silicate or
organosilicate dielectric film, and then seal surface pores of the
silicate or organosilicate dielectric film, when the film is
porous.
A suitable surface modification agent composition includes one or
more surface modification agents able to remove silanol groups from
the surface of an etched and/or ashed organosilicate glass
dielectric film that it is desired to render hydrophobic. These may
be silane, silazane, silanols, or carboxysilyl. For example, a
surface modification agent is a compound having a formula selected
from the Formulas:
(1) [--SiR.sub.2NR'--]n where n>2 and may be cyclic; (2)
R.sub.3SiNR'SiR.sub.3, (3) (R.sub.3Si).sub.3N; (4)
R.sub.3SiNR'.sub.2; (5) R.sub.2Si(NR.sub.2').sub.2; (6)
RSi(NR.sub.2').sub.3; (7) R.sub.xSiCl.sub.y, (8)
R.sub.xSi(OH).sub.y, (9) R.sub.3SiOSiR'.sub.3, (10)
R.sub.xSi(OR').sub.y, (11) R.sub.xSi(OCOR').sub.y, (12)
R.sub.xSiH.sub.y; (13) R.sub.xSi[OC(R').dbd.R''].sub.4-x and
combinations thereof, wherein x is an integer ranging from 1 to 3,
y is an integer ranging from 1 to 3 such that y=4-x; each R is an
independently selected from hydrogen and a hydrophobic organic
moiety. The R groups are preferably independently selected from the
group of organic moieties consisting of alkyl, aryl and
combinations thereof. The R' group may be H, alkyl, aryl, or
carbonyl such as COR, CONR, CO.sub.2R. The R'' may be alkyl or
carbonyl such as COR, CONR, CO.sub.2R
For all surface modification agents, the reactive silyl group must
contain a hydrolyzable leaving group such as but not limited to
--Cl, --Br, --I, --OR, --NR.sub.X (where x=1-2), --OCOR,
--OCO.sub.2R, --NRCOR, --NRCO.sub.2R, --NRCONR, --SR, --SO.sub.2R.
For reaction of the surface modification agent, hydrolysis may
occur spontaneously with moisture present during the surface
modification agent application and process, or pre-hydrolysis may
be forced during the formulation process.
The alkyl moiety is either functionalized or non-functionalized and
is derived from groups of straight alkyl, branched alkyl, cyclic
alkyl and combinations thereof, and wherein said alkyl moiety
ranges in size from C.sub.1 to about C.sub.18. The
functionalization may be a carbonyl, a halide, an amine, an
alcohol, an ether, a sulfonyl or sulfide. The aryl moiety is
substituted or unsubstituted and ranges in size from C.sub.5 to
about C.sub.18. Preferably the surface modification agent is an
acetoxysilane, or, for example, a monomer compound such as
acetoxysilane, acetoxytrimethylsilane, diacetoxysilane,
triacetoxysilane, acetoxytrimethylsilane, diacetoxydimethylsilane,
methyltriacetoxysilane, phenyltriacetoxysilane,
diphenyldiacetoxysilane, methyltriethoxysilane,
dimethyldiethoxysilane, trimethylethoxysilane,
methyltrimethoxysilane, dimethyldimethoxysilane,
trimethylmethoxysilane, methyltrichlorosilane,
dimethyldichlorosilane, trimethylchlorsilane, methylsilane,
dimethylsilane, trimethylsilane, hexamethyldisilazane,
hexamethylcyclotrisilazane, bis(dimethylamino)dimethylsilane,
bis(diethylamino)dimethylsilane, tris(dimethylamino)methylsilane,
tris(dimethylamino)phenylsilane, tris(dimethylamino)silane,
dimethylsilyldiformamide, dimethylsilyldiacetamide,
dimethylsilyldiisocyante, trimethylsilylisocyanate,
methylsilyltriisocyanate, 2-trimethylsiloxypent-2-ene-4-one,
n-(trimethylsilyl)acetamide, 2-(trimethylsilyl) acetic acid,
n-(trimethylsilyl)imidazole, trimethylsilylpropiolate,
trimethylsilyl(trimethylsiloxy)-acetate, nonamethyltrisilazane,
hexamethyldisiloxane, trimethylsilanol, triethylsilanol,
triphenylsilanol, t-butyldimethylsilanol, diphenylsilanediol,
trimethoxysilane, triethoxysilane, trichlorosilane, and
combinations thereof. In one noteworthy embodiment, the surface
modification agent is methyltriacetoxysilane. In a preferred
embodiment the surface modification agent is
dimethyldiacetoxysilane.
Additional surface modification agents include multifunctional
surface modification agents as described in detail in U.S. Pat. No.
6,208,014, incorporated by reference herein, as described above.
Such multifunctional surface modification agents can be applied in
either vapor form, gaseous form, or by chemical vapor depositing,
optionally with or without co-solvents.
Suitable co-solvents include, e.g., ketones, such as acetone,
diisopropylketone, 2-heptanone, 3-pentanone, and others, as
described in detail in co-owned U.S. Pat. No. 6,395,651, the
disclosure of which is incorporated by reference herein.
For example, as described in detail in U.S. Pat. No. 6,208,014,
certain preferred surface modification agents will have two or more
functional groups and react with surface silanol functional groups
while minimizing mass present outside the structural framework of
the film, and include, e.g., surface silanols may condense with
suitable silanols such as R.sub.xSi(OH.sub.2).sub.4-x
wherein x=1-3, and each R is independently selected moieties, such
as H and/or an organic moiety such as an alkyl, aryl or derivatives
of these. When R is an alkyl, the alkyl moiety is optionally
substituted or unsubstituted, and may be straight, branched or
cyclic, and preferably ranges in size from C.sub.1 to about
C.sub.18, or greater, and more preferably from C.sub.1 to about
C.sub.8. When R is aryl, the aryl moiety preferably consists of a
single aromatic ring that is optionally substituted or
unsubstituted, and ranges in size from C.sub.5 to about C.sub.18,
or greater, and more preferably from C.sub.5 to about C.sub.8. In a
further option, the aryl moiety is a heteroaryl.
In another embodiment, alkoxy silanes may be used as the surface
modification agent, e.g. suitable alkoxy silanes such as
R.sub.xSi(OR').sub.4-x
wherein R are independently selected moieties, such as H and/or an
organic moiety such as an alkyl, aryl or derivatives of these; R'
are independently selected alkyl or aryl moieties. When R or R' is
an alkyl, the alkyl moiety is optionally substituted or
unsubstituted, and may be straight, branched or cyclic, and
preferably ranges in size from C.sub.1 to about C.sub.18, or
greater, and more preferably from C.sub.1 to about C.sub.8. When R
or R' is aryl, the aryl moiety preferably consists of a single
aromatic ring that is optionally substituted or unsubstituted, and
ranges in size from C.sub.5 to about C.sub.18, or greater, and more
preferably from C.sub.5 to about C.sub.8. In a further option, the
aryl moiety is a heteroaryl. Thus, the R groups independently
selected from H, methyl, ethyl, propyl, phenyl, and/or derivatives
thereof, provided that at least one R is organic. In one
embodiment, both R groups are methyl, and a tri-functional surface
modification agent is methyltrimethoxysilane.
In another embodiment, a suitable silane according to the invention
has the general formula of R.sub.XSi(NR.sub.2).sub.4-x
wherein X=1-3, R are independently H, alkyl and/or aryl. When any R
are alkyl and/or aryl. In preferred embodiments, R is selected from
H, CH.sub.3, C.sub.6H.sub.5, and R.sub.2 and R.sub.3 are both
CH.sub.3. Thus tri-functional surface modification agents include,
e.g., tris(dimethylamino)methylsilane,
tris(dimethylamino)phenylsilane, and/or tris(dimethylamino)silane.
In addition, disubstituted silanes may be used such as
hexamethylcyclotrisilazane, bisdimethylaminodimethylsilane, and
bisdiethylaminodimethylsilane.
In yet another embodiment, a suitable silane according to the
invention has the general formula of
R.sub.xSi(ON.dbd.CR.sub.2).sub.4-x or
R.sub.xSi[OC(R').dbd.R''].sub.4-x
wherein x=1-3 and the R groups are independently H, alkyl and/or
aryl, R' may be H, alkyl, aryl, alkoxy or aryloxy, and R'' may be
alkyl or carbonyl. Thus modification agents include, e.g.,
methyltris(methylethylketoxime)silane or
2-trimethylsiloxypent-2-ene-4-one respectively.
In yet another embodiment, a suitable silane according to the
invention has the general formula of R.sub.xSi(NCOR.sub.2).sub.4-x
or R.sub.xSi(NCO).sub.4-x wherein x=1-3, R groups are independently
H, alkyl and/or aryl. Thus surface modification agents include,
e.g., dimethylsilyldiformamide, dimethylsilyldiacetamide,
dimethylsilyldiisocyante, trimethylsilyltriisocyante.
In yet a further embodiment, a suitable silane according to the
invention has the general formula of R.sub.xSiCl.sub.4-x wherein
x=1-3, is H, alkyl or aryl. In one preferred embodiment, R.sub.x is
CH.sub.3. Thus tri-functional surface modification agents include,
e.g., methyltrichlorosilane.
In a more preferred embodiment, the surface modification agent
includes one or more organoacetoxysilanes which have the following
general formula, (R.sub.1).sub.xSi(OCOR.sub.2).sub.y
Preferably, x is an integer ranging in value from 1 to 2, and x and
y can be the same or different and y is an integer ranging from
about 2 to about 3, or greater.
Useful organoacetoxysilanes, including multifunctional
alkylacetoxysilane and/or arylacetoxysilane compounds, include,
simply by way of example and without limitation,
methyltriacetoxysilane ("MTAS"), dimethyldiacetoxysilane (DMDAS),
phenyltriacetoxysilane and diphenyldiacetoxysilane and combinations
thereof.
The component capable of alkylating or arylating silanol moieties
of the organosilicate glass dielectric film via silylation is
usually present in the surface modification agent composition in an
amount of from about 0.1 weight percent to about 100 weight
percent, more usually from about 1 weight percent to about 50
weight percent, and most usually from about 3 weight percent to
about 30 weight percent.
The surface modification agent composition may optionally contain
one or more of the activating agents listed above. When
incorporated within the surface modification agent composition, the
activating agent is usually present in an amount of from about
0.0001 weight percent to about 10 weight percent, more usually from
about 0.001 weight percent to about 1 weight percent, and most
usually from about 0.01 weight percent to about 0.1 weight percent
of the surface modification agent composition.
Optionally, the surface modification agent composition includes a
solvent composition capable of solubilizing with the component
capable of alkylating or arylating silanol moieties of the
organosilicate glass dielectric film via silylation, and the
activating agent. Suitable solvents compositions non-exclusively
include, for example, ketones, ethers, esters, hydrocarbons,
alcohols, carboxylic acids, amides, and combinations thereof.
Useful solvents non-exclusively include 3-pentanone, 2-heptanone,
gammabutyrolactone, propylene glycol methyl ether acetate, acetic
acid, and combinations thereof. The solvent, when employed, is
usually present in the surface modification agent composition in an
amount of from about 0 weight percent to about 99.9 weight percent,
more usually from about 50 weight percent to about 99 weight
percent, and most usually from about 70 weight percent to about 97
weight percent. In another embodiment of the invention, the surface
modification agent composition includes a supercritical solvent,
such as supercritical carbon dioxide.
Optionally, the surface modification agent composition includes a
corrosion inhibitor, such as a corrosion inhibitor which chelates
with copper. Such may include benzotriazole, tolyltriazole, and
combinations thereof. The corrosion inhibitor, when employed, is
usually present in the surface modification agent composition in an
amount of from about 0.001 weight percent to about 10 weight
percent, more usually from about 0.01 weight percent to about 5
weight percent, and most usually from about 0.2 weight percent to
about 1 weight percent.
The surface modification agent composition is formed by blending
the selected components into a mixture. The surface modification
agent composition contacts the damaged silica dielectric film as a
vapor, gas, and/or plasma. Contacting by applying a gas or vapor of
the surface modification agent to the film is preferred. Such
contacting may be conducted at a temperature of from about
0.degree. C. to about 450.degree. C., preferably from about
20.degree. C. to about 450.degree. C. The contacting may be
conducted for from about 1 second to about 2 hours, preferably from
about 10 seconds to about 30 minutes. Preferably the contacting is
conducted under controlled chamber conditions using a carrier gas,
such as nitrogen, helium or argon which serves to control the
chamber conditions (pressure) and to uniformly distribute the
reactants, i.e. the surface modification composition including
activation agents and solvents used. Preferably the carrier gas is
miscible with these components.
The surface modification agent composition may also be applied by
chemical vapor deposition techniques. Chemical vapor deposition
processes are well known to those skilled in the art and chemical
vapor deposition reactors are widely commercially available. One
suitable reactor is model SK-23-6-93 commercially available from
Vactronic Equipment Labs of Bohemia, New York. Others may be
obtained from ASM International, Novellus Systems, or Applied
Materials. The chemical vapor depositing is conducted by heating at
a relatively low temperature of from about 100.degree. C. to about
.degree. C., preferably from about 200.degree. C. to about
400.degree. C. and more preferably from about 350.degree. C. to
about 400.degree. C. The heating during the chemical vapor
depositing is conducted at a relatively short time of from about 30
seconds to about 3 minutes. In the process, film on substrate is
placed in the chemical vapor deposition reactor. The reactor is
sealed and evacuated to less than one millitorr of ambient
background gas pressure. In the preferred embodiment, a flow of
surface modification agent composition and an inert gas, such as
nitrogen, helium or argon is established and the chamber is heated
until it is stabilized to the desired reaction temperature and gas
flow rate. The gas flow ranges from 0 to about 5,000 sccm (standard
cubic centimeters per minute measured at 0.degree. C. and
atmospheric pressure) or preferably from about 500 to about 2,000
sccm and most preferably about 1,000 sccm. The reactor gas pressure
preferably ranges from about 0.1 to about 760 torr, more preferably
from about 0.2 to about 400 torr and most preferably from about
0.25 to about 2.0 torr.
In one case, the surface modification agent composition treatment
is conducted until carbon containing moieties are added to the
silicate or organosilicate dielectric film. Usually this is through
a depth thereof such that at least 10% of the silanol moieties or
bonds created by removal of carbon containing moieties from the
silicate or organosilicate dielectric film are silylated. In
another case, when the silicate or organosilicate dielectric film
has pores, the surface modification treatment is conducted under
conditions sufficient to seal pores at a surface of the
organosilicate dielectric film to a depth of about 50 .ANG. or
less. 15. The pores at the surface of the silicate or
organosilicate dielectric film are preferably sealed, to such an
extent that a subsequent exposure to (i) precursors for chemical
vapor deposition of nitride, carbide, metals, or (ii) non-etching
wet cleaning materials does not allow a penetration thereof to a
depth greater than 5 times the maximum pore size.
Optionally the inventive method further comprises the subsequent
step of subjecting the silicate or organosilicate dielectric film
to a treatment sufficient to effect (i) an increased addition of
carbon containing moieties to the silicate or organosilicate
dielectric film or (ii) an increased sealing of surface pores of
the silicate or organosilicate dielectric film; or (iii) first an
increased addition of carbon containing moieties to the silicate or
organosilicate dielectric film and then an increased sealing of
surface pores of the silicate or organosilicate dielectric film or
(iv) removing at least some residual activating agent, surface
modification agent, by-products; and combinations thereof. This may
be done by heating, ultraviolet radiation, plasma energy, electron
beam, ion beam or combinations thereof, under conditions to effect
such results. Heating may be done at a temperature of from about
20.degree. C. to about 450.degree. C., preferably from about
100.degree. C. to about 400.degree. C. for from about 10 seconds to
about 120 minutes, preferably from about 10 seconds to about 120
minutes.
In yet another embodiment, a wet clean using chemicals such as
AP395 or dilute HF is performed after the above-mentioned
embodiments. The wet clean is useful to remove any resist residues
remaining after the ash. Untreated low-k dielectric materials after
etch and ash are prone to attack by the wet clean agents. The
surface modification agent treatment significantly improves
resistance of the low-k dielectric to attack by wet clean.
In yet another embodiment, the wet clean can be performed before
the bake process in the first contemplated embodiment. The high
temperature bake step is performed after the wet clean. An
advantage of this method can be that the wet clean can remove
excess surface modification agent and any reaction product. This
can result in lower volatile components in the dielectric material
and a cleaner copper surface. Both can result in an improved long
term reliability.
In another embodiment, the surface modification agent composition
is provided by exposing the dielectric film to a plasma which is
derived from any of the above mentioned surface modification agent.
In a typical procedure, the organosilicate glass dielectric film is
placed in a plasma generating chamber, such as a plasma enhanced
chemical vapor deposition (PECVD) system; the vapor of a surface
modification agent composition and argon vapor are passed through
the plasma generating chamber; then an RF energy source is
activated to create a plasma; the argon gas is included to help
promote the formation of plasma. The plasma is composed of ionic
fragments derived from the surface modification agent composition;
for example, the ion fragment CH.sub.3Si.sup.+ is generated from
methylsilane (CH.sub.3SiH.sub.3). This fragment reacts with silanol
groups to form hydrophobic Si--CH.sub.3 moieties. Any of the above
mentioned surface modification agent compositions can be used for
this plasma induced surface treatment.
Other reagents for plasma induced surface modification agent
compositions include aldehydes, esters, acid chlorides, and ethers.
Suitable aldehydes include acetaldehyde and benzaldehyde; suitable
esters include ethyl acetate and methyl benzoate; suitable acid
chlorides include acetyl chloride and benzyl chloride; and suitable
ethers include diethyl ether and anisole. A wide variety of single
wafer or multiple wafer (batch) plasma systems can be used for this
process; these systems include so called downstream ashers, such as
the Gasonics L3510 photoresist asher, PECVD dielectric deposition
systems such as the Applied Materials P5000, or reactive ion etch
("RIE") systems. Broadly, the conditions for the plasma process are
within the following ranges: chamber temperature, 20.degree. C. to
450.degree. C.; RF power, 50 W to 1000 W; chamber pressure, 0.05 to
100 torr; plasma treatment time, 5 seconds to 5 minutes; and
surface modification flow rate, 100-2000 sccm; inert gas flow rate
(typically argon), 100-2000 sccm.
Preferably the overall process of is conducted within a cluster
tool having a chamber adapted for each if the inventive steps, such
as a chamber for depositing a silicate or organosilicate dielectric
film on a substrate. A vapor, gas or chemical vapor deposition
chamber, and means for transferring the film on substrate among the
various chambers. The treatment in the chambers and the
transferring among the chambers are preferably conducted while
continuously maintaining vacuum conditions. Cluster tools for the
processing of semiconductor wafers are well known in the art and
are widely commercially available. Such may be exemplified by U.S.
Pat. Nos. 5,259,881; 5,280,219; 5,730,801; 5,613,821 and
5,380,682.
Wafers are continuously maintained in an isolated environment at a
constant vacuum pressure level, and transferred into and out of an
external atmospheric pressure environment through one or more
access ports or load-locks. In a typical system, a cassette or
carrier with a series of wafers is placed at an interface port of
the cluster tool and latches release the port door. A manipulator
robot picks up the cassette or individual wafer and directs them to
desired processing stations within the equipment. After processing,
the reverse operation takes place. Such a wafer processing
technique essentially eliminates contaminates since treatment takes
place after the wafers are sealed in the internal vacuum
environment, and they are not removed prior to completion of
processing. The configuration achieves a significant improvement
over the conventional handling of open cassettes inside a clean
room. In addition, since the vacuum is not broken from step to
step, the use of cluster tools increases process productivity and
reduces defect levels. The use of a cluster tool significantly aids
semiconductor processing throughput. As a result chemical vapor
deposition and electron beam treatment can be done directly within
a cluster tool without breaking vacuum or removal of the substrate
from the cluster tool.
The artisan will appreciate that the invention is also contemplated
to encompass microelectronic devices, such as semiconductor devices
or ICs manufactured using these methods are also a part of the
present invention.
The microelectronic devices, dielectric layers and materials may be
utilized or incorporated into any suitable electronic component.
Electronic components, as contemplated herein, are generally
thought to comprise any dielectric component or layered dielectric
component that can be utilized in an electronic-based product.
Contemplated electronic components comprise circuit boards, chip
packaging, dielectric components of circuit boards, printed-wiring
boards, and other components of circuit boards, such as capacitors,
inductors, and resistors.
Electronic-based products can be "finished" in the sense that they
are ready to be used in industry or by other consumers. Examples of
finished consumer products are a television, a computer, a cell
phone, a pager, a palm-type organizer, a portable radio, a car
stereo, and a remote control. Also contemplated are "intermediate"
products such as circuit boards, chip packaging, and keyboards that
are potentially utilized in finished products.
Electronic products may also comprise a prototype component, at any
stage of development from conceptual model to final scale-up
mock-up. A prototype may or may not contain all of the actual
components intended in a finished product, and a prototype may have
some components that are constructed out of composite material in
order to negate their initial effects on other components while
being initially tested. Electronic products and components may
comprise layered materials, layered components, and components that
are laminated in preparation for use in the component or
product.
The following non-limiting examples serve to illustrate the
invention.
EXAMPLE 1
System Configuration A
The configuration shown in FIG. 1 was used to perform a silylation
treatment. A reservoir was filled with 100% dimethyldiacetoxysilane
(DMDAS). Reservoir temperature is adjustable. A wafer with plasma
damaged porous low-k (NANOGLASS-E, commercially available form
Honeywell International, Sunnyvale, Calif.) was placed in the
reaction chamber, evacuated for a 30 min dehydration step and
during evacuation the film was heated to a desired temperature. The
film was exposed to DMDAS vapor for desired time. The wafer was
then removed from the reaction chamber and baked in N2 ambient on
hot plates at 125.degree. C., 200.degree. C. and 350.degree. C. for
1 minute each. The properties of the low-k film at different
process steps are as follows. An increase in chamber process
temperature increased % carbon repair and decreased dielectric
constant. An increase in exposure time decreased carbon repair for
lower temperature, but increased carbon repair for higher
temperature process.
TABLE-US-00001 Pumpdown Prior DMDAS Contact Angle % Carbon Chamber
DMDAS Exposure (NGE) Post Restoration Post k(Hg) Post Process Flow
Temp (C.) Exposure (min) Time (min) 350 HP 350 HP 350 HP Post Cure
>80 2.22 Damaged NGE <10 2.85 DMDAS Only 45 30 1 25 2.57
DMDAS Only 45 30 10 10 2.58 DMDAS Only 150 30 1 43 2.53 DMDAS Only
150 30 10 65 2.54
EXAMPLE 2
System Configuration A
The configuration shown in FIG. 1 was used to perform a silylation
treatment. A reservoir was filled with 100% DMDAS. The reservoir
temperature is adjustable. A wafer with plasma damaged porous low-k
(NANOGLASS-E) was placed in the reaction chamber, evacuated for a
30 min dehydration step and during evacuation the film was heated
to a desired temperature. The film was exposed to DMDAS vapor for 1
min. Expose to NH.sub.3 for 1 minute. The wafer was then removed
from the reaction chamber and baked in N2 ambient on hot plates at
125.degree. C., 200.degree. C. and 350.degree. C. for 1 min each.
The properties of the low-k film at different process steps are as
follows. An increase in chamber process temp with 1 minute exposure
decreased % carbon repair, but decreased dielectric constant. The
condition with increased exposure time and higher chamber temp gave
decreased % carbon repair and decreased dielectric constant.
TABLE-US-00002 Pumpdown Prior DMDAS Contact Angle % Carbon Chamber
DMDAS Exposure Exposure (NGE) Post Restoration k(Hg) Post Process
Flow Temp (C.) (min) Time (min) 350 HP Post 350 HP 350 HP Post Cure
>80 2.22 Damaged NGE <10 2.85 DMDAS + NH3 45 30 1 42 2.64
DMDAS + NH3 45 30 10 81 2.59 DMDAS + NH3 150 30 1 28 2.46 DMDAS +
NH3 150 30 10 46 2.51
EXAMPLE 3
System Configuration B
The configuration shown in FIG. 2 was used to perform a silylation
treatment. A bubbler was filled with 100% DMDAS and was maintained
at a constant temperature of 45.degree. C. Nitrogen was used to
bubble through DMDAS and carry DMDAS through chamber at desired
flow. A wafer with plasma damaged porous low-k (NANOGLASS-E) was
placed in the furnace tube evacuated for 30 min dehydration step
while being heated to a desired temperature. The film was exposed
to DMDAS vapor for 30 minutes. A final anneal was performed in the
furnace tube at a desired temperature. The wafer was then removed
from furnace tube. The properties of the low-k film at different
process steps are as follows. Varied chamber temperature conditions
gave similar contact angle. The % carbon repair varied throughout
temperature range. A dielectric constant of 2.29 was result for one
temperature condition.
TABLE-US-00003 Pumpdown Prior DMDAS Contact Angle % Carbon Chamber
Final DMDAS Exposure Exposure (NGE) Post Restoration k(Hg) Post
Process Flow Temp (C.) Anneal (C.) (min) Time (min) 350 HP Post 350
HP 350 HP Post Cure >80 2.22 Damaged NGE <10 3.00 DMDAS ONLY
200 350 30 30 125 118 DMDAS ONLY 200 350 30 30 108 94 DMDAS ONLY
275 350 30 30 126 217 DMDAS ONLY 275 350 30 30 116 72 2.29 DMDAS
ONLY 350 425 30 30 125 49 DMDAS ONLY 425 425 30 30 123 95
EXAMPLE 4
System Configuration B
The configuration shown in FIG. 2 was used to perform a silylation
treatment. A bubbler was filled with 100% DMDAS and was maintained
at a constant temperature of 45.degree. C. Nitrogen was used to
bubble through DMDAS and carry DMDAS through furnace tube at a
desired flow. A wafer with plasma damaged porous low-k
(NANOGLASS-E) was placed in the furnace tube evacuated for 30
minutes dehydration step and heated to a desired chamber
temperature. The film was exposed to NH.sub.3 flow for 32 minutes.
The film was exposed to DMDAS vapor for 30 minutes. A final anneal
was performed in this tube at a desired temperature. The wafer was
then removed from furnace tube. The properties of the low-k film at
different process steps are as follows. Varied chamber temperature
gave similar contact angles all >115 degrees. All samples gave
>80% carbon repair and a decrease in dielectric constant from
the damaged dielectric of 3.00.
TABLE-US-00004 Pumpdown Prior DMDAS Contact Angle % Carbon Chamber
Final DMDAS Exposure Exposure (NGE) Post Restoration Post k(Hg)
Post Process Flow Temp (C.) Anneal (C.) (min) Time (min) 350 HP 350
HP 350 HP Post Cure >80 2.22 Damaged NGE <10 3.00 DMDAS + NH3
200 350 30 30 121 82 2.47 DMDAS + NH3 275 350 30 30 123 245 DMDAS +
NH3 350 350 30 30 115 165 2.33
EXAMPLE 5
System Configuration C
The configuration shown in FIG. 3 was used to perform a silylation
treatment. A jacketed reservoir was filled with 100% DMDAS and
maintained at 55.degree. C. A wafer with plasma damaged porous
low-k (NANOGLASS-E) was placed in the reaction chamber, evacuated
for a dehydration step and heated to a desired chamber temperature.
The plasma damaged porous low-k film was exposed to DMDAS vapor for
5 minutes. The film was then removed from the reaction chamber and
baked in N.sub.2 ambient on hot plates at 125.degree. C.,
200.degree. C. and 350.degree. C. for 1 minute each. The properties
of the low-k film at different process steps are as follows. An
increase in dehydration step for the 110.degree. C. condition gave
an increase in contact angle, increase in carbon repair and a
decrease in dielectric constant. Dehydration step of the
300.degree. C. chamber process temperature had little effect on
contact angle, % carbon repair and dielectric constant. Overall
higher chamber temperature processing gave better results.
TABLE-US-00005 Contact Angle % Carbon Chamber Pumpdown Prior (NGE)
Post Restoration Post k(Hg) Post Process Flow Temp (C.) DMDAS
Exposure 350 HP 350 HP 350 HP Post Cure >80 2.22 Damaged NGE
<10 3.00 DMDAS Only 110 10 97 14 2.56 DMDAS Only 110 900 103 24
2.53 DMDAS Only 300 10 84 30 2.45 DMDAS Only 300 900 87 31 2.47
EXAMPLE 6
System Configuration C
The configuration shown in FIG. 3 was used to perform a silylation
treatment. A jacketed reservoir was filled with 100% DMDAS and
maintained at 55.degree. C. A wafer with plasma damaged porous
low-k (NANOGLASS-E) was placed in the reaction chamber, evacuated
for a dehydration step and heated to a desired chamber temperature.
The plasma damaged porous low-k film was exposed to NH.sub.3 gas
for 5 min. After 5 minutes NH.sub.3 gas exposure while NH.sub.3 is
flowing chamber is opened up to DMDAS gas. The film was then
removed from the reaction chamber and baked in N2 ambient on hot
plates at 125.degree. C., 200.degree. C. and 350.degree. C. for 1
minute each. The properties of the low-k film at different process
steps are as follows. The dehydration step prior to introduction of
NH.sub.3 had little effect on final results within a given
temperature range. This could be the result of in the presence of
NH.sub.3 and/or increased dehydration step during the NH.sub.3
step. Increased chamber temperature gave decreased contact angle,
increased carbon repair and decreased dielectric constant.
TABLE-US-00006 Contact Angle % Carbon Chamber Pumpdown Prior to
(NGE) Post Restoration k(Hg) Post Process Flow Temp (C.) Exposure
to NH3 350 HP Post 350 HP 350 HP Post Cure >80 2.22 Damaged NGE
<10 3.00 NH3 + DMDAS 110 10 114 32 2.45 NH3 + DMDAS 110 900 114
25 2.46 NH3 + DMDAS 300 10 86 39 2.40 NH3 + DMDAS 300 900 85 45
2.40
EXAMPLE 7
System Configuration C
The configuration shown in FIG. 3 was used to perform a silylation
treatment. A jacketed reservoir was filled with 100% DMDAS and
maintained at 55.degree. C. A wafer with plasma damaged porous
low-k (NANOGLASS-E) was placed in the reaction chamber and heated
to a desired chamber temperature. A desired pumpdown (degas) step
prior to gas exposure. The film was exposed to NH.sub.3 gas for 5
minutes The chamber was evacuated for 10 sec and than the chamber
is opened up to DMDAS gas for 5 minutes. The wafer was then removed
from the reaction chamber and baked in N.sub.2 ambient on hot
plates at 125.degree. C., 200.degree. C. and 350.degree. C. for 1
minute each. The properties of the low-k film at different process
steps are as follows. The dehydration step prior to introduction of
NH.sub.3 had little effect on final results within a given
temperature range. This could be the result of in the presence of
NH.sub.3 and/or increased dehydration step during the NH.sub.3
step. Increased chamber temperature gave decreased contact angle,
increased carbon repair and decreased dielectric constant.
TABLE-US-00007 % Carbon Chamber Pumpdown Prior to Contact Angle
Restoration k(Hg) Post Process Flow Temp (C.) Exposure to NH3 (NGE)
Post 350 HP Post 350 HP 350 HP Post Cure >80 2.22 Damaged NGE
<10 3.00 NH3 + pumpdown + DMDAS 110 10 102 17 2.53 NH3 +
pumpdown + DMDAS 110 900 104 22 2.53 NH3 + pumpdown + DMDAS 300 10
85 25 2.48 NH3 + pumpdown + DMDAS 300 900 86 45 2.48
EXAMPLE 8
System Configuration A
The configuration shown in FIG. 1 was used to perform a silylation
treatment. A reservoir was filled with 100%
Hexamethylcyclotrisilazane (HMCTZ). Reservoir temperature is
adjustable. This study maintained reservoir temp of 45.degree. C. A
wafer with plasma damaged porous low-k (NANOGLASS-E) was placed in
the reaction chamber, evacuated for 30 min and during evacuation
the film was heated to a desired temperature chamber temperature.
The film was exposed to HMCTZ vapor for 1. The wafer was then
removed from the reaction chamber and baked in N2 ambient on hot
plates at 125.degree. C., 200.degree. C. and 350.degree. C. for 1
minute each. The properties of the low-k film at different process
steps are as follows. Using HMCTZ for repair of lowered the
dielectric constant from 2.92 to 2.45.
TABLE-US-00008 % Carbon Chamber Pumpdown Prior to Contact Angle
Restoration k(Hg) Post Process Flow Temp (C.) Exposure to HMCTZ
(NGE) Post 350 HP Post 350 HP 350 HP Post Cure >80 2.22 Damaged
NGE <10 2.92 HMCTZ 150 30 2.46 HMCTZ 150 30 2.45
EXAMPLE 9
In order to understand the temperature dependence of the
silanization reaction on the surface, the deposition temperature
was varied from 110.degree. C. to 400.degree. C. The different
temperature would result in variation in moisture content and gas
molecular activity on the surface, which in turn, result in
different chemistry to occur. Process conditions used: ammonia flow
rate 20 sccm (or 80 sccm), DMDAS reservoir temperature, 55.degree.
C., total pressure 1.5 torr, bake at 350.degree. C. oven
TABLE-US-00009 Substrate temperature, Contact Dielectric Carbon
.degree. C. angle constant restoration 200, 6, (7) 78, (83) 2.67,
(2.60) 300, 8, (9) 102 (57) 2.54, (2.64) 20 (12) 400, 13, (12) 84,
(85) 2.52, (2.47) 31 (14)
The higher the temperature, the lower the K value.
EXAMPLE 10
In order to understand the effect of gas dose on the silanization
reaction, a flow rate of the silane gas was varied. Flow rate was
calculated by changing reservoir temperature of the silane solution
and a pressure in the chamber. The reservoir temperature was varied
by heating the reactant solution in a pyrex container. Process
conditions used: ammonia flow rate 80 sccm, total pressure 1.5
torr, bake at 350.degree. C. oven, wafer temperature, 400.degree.
C.
TABLE-US-00010 Contact Dielectric Carbon Defect count Gas flow
rate, sccm angle constant restoration (defect density) 65, 4 89
2.46 24 55, 12 85 2.47 27
No difference in K value by varying reservoir temperature
EXAMPLE 11
In order to understand the effect of gas dose on the silanization
reaction, a flow rate of the ammonia gas was varied. The reservoir
temperature was varied by heating the reactant solution in a pyrex
container. Process conditions used: total pressure 1.5 torr, bake
at 350.degree. C. oven, wafer temperature, 400.degree. C., DMDAS
reservoir 55.degree. C.
TABLE-US-00011 Contact Carbon Gas flow rate, sccm angle Dielectric
constant restoration 20, 13 84 2.52 32 80, 12 85 2.47 27
The higher the ammonia gas flow rate, the lower the K value.
EXAMPLE 12
To understand the effect of bake condition (in-situ and oven) on K
value, the processed wafers were baked in either the chamber
(in-situ) or TEL oven. Process conditions used: ammonia flow rate
50 sccm, total pressure 2.0 torr, wafer temperature, 300.degree.
C., Reservoir temperature 55.degree. C.
TABLE-US-00012 Dielectric Carbon Defect count Bake condition
Contact Angle constant restoration (defect density) Chamber, 12 86
2.47 72 TEL HP, 12 88 2.45 86
Slight decrease in contact angle and carbon restoration using P5000
for final thermal treatment compared to TEL HP. Slight increase in
dielectric constant using P5000 instead of TEL HP.
While the present invention has been particularly shown and
described with reference to preferred embodiments, it will be
readily appreciated by those of ordinary skill in the art that
various changes and modifications may be made without departing
from the spirit and scope of the invention. It is intended that the
claims be interpreted to cover the disclosed embodiment, those
alternatives which have been discussed above and all equivalents
thereto.
* * * * *